Courts are political. The Supreme Court is supremely political. That's just reality. And ever since Lawrence v. Texas[3], the Court has been moving toward full acceptance of LGBT people:

The Supreme Court invalidated the Texas law but also went further by explicitly overruling Bowers – the significance of which was not lost on dissenting Justice Antonin Scalia, who presciently complained that the ruling "leaves on pretty shaky grounds state laws limiting marriage to opposite-sex couples." Indeed it does.

And it's hard to imagine that the Supreme Court could possibly, in 2012, make a broad statement against gay marriage. I just don't see it happening. I think Scalia will fulminate, but a majority of the Court will rule in the spring that lesbian and gay people have a fundamental right to marry.

You read it here first.

UPDATE: HuffPo's legal eagle disagrees with me[4], saying a pro-same-sex marriage ruling would be too "bold." I think he's wrong; the vast majority of Americans under 40 have no problem with same-sex marriage, and in a few years, anything other than a "bold" decision will look embarassingly dumb.